3,262 research outputs found
Exploratory Analysis of the Airspace Throughput and Sensitivities of an Urban Air Mobility System
The use of small, vertical-takeoff and landing aircraft to provide efficient, high-speed, ondemand passenger transportation within a metropolitan area (e.g. intra-city transportation) is a topic of increasing interest and investment within the aerospace and transportation communities. Preliminary, mostly vehicle-level analysis suggests that passenger-carrying Urban Air Mobility has the potential to provide meaningful door-to-door trip time savings compared to identical trips taken solely by automobile, even for relatively short trips of a few tens of miles. Subsequent analysis has shown that if such trips can be conducted at costs competitive with ground transportation, the demand for such flight operations, not surprisingly, becomes unprecedented by historical airspace operations counts, raising fundamental questions regarding feasibility, practicality, capacity and basic system attributes such as separation criteria. In this paper, we conduct a preliminary assessment of vertipad requirements and en route separation minima relative to the feasibility of large-scale urban aviation operations. This analysis is acknowledged as being far from comprehensive and is intended to help define the initial boundaries of an airspace system compatible with enabling high-volume operations
THE AMERICAN YEAR-BOOK OF MEDICINE AND SURGERY, being a Yearly Digest of Scientific Progress and Authoritative Opinion in all Branches of Medicine and Surgery, under the general editorial charge of GEORGE M. GOULD, M.D. SURGERY. Philadelphia and London: W. B. Saunders & Company, 1902
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A Family Narration of Disability Experience in Iran
Focusing on Mohsen Hosseini Taha, a person with cerebral palsy, and his family, this research explores the social and mental consequences of having a member with physical disability on a typical Iranian family. The oral narratives used in this research have been collected in a series of in-depth interviews with Mohsen, his parents, and his only sister, in 4 sessions or 10 hours of face-to-face interviews. The analysis of the interviews addresses several questions: How was Mohsenâs disability initially diagnosed and what were his parentsâ first reactions? What have been the social obstacles facing Mohsenâs familyâs efforts to practice a routine life within Iranian society? How has Mohsenâs disability affected his familyâs life socially and mentally throughout the years? Finally, how well do core concepts of Western disability studies apply within a typical non-western family? The real names of the participants have been used with their permission
A method for diagnosing time dependent faults using model-based reasoning systems
This paper explores techniques to apply model-based reasoning to equipment and systems which exhibit dynamic behavior (that which changes as a function of time). The model-based system of interest is KATE-C (Knowledge based Autonomous Test Engineer) which is a C++ based system designed to perform monitoring and diagnosis of Space Shuttle electro-mechanical systems. Methods of model-based monitoring and diagnosis are well known and have been thoroughly explored by others. A short example is given which illustrates the principle of model-based reasoning and reveals some limitations of static, non-time-dependent simulation. This example is then extended to demonstrate representation of time-dependent behavior and testing of fault hypotheses in that environment
A high-fidelity, six-degree-of-freedom batch simulation environment for tactical guidance research and evaluation
A batch air combat simulation environment, the tactical maneuvering simulator (TMS), is presented. The TMS is a tool for developing and evaluating tactical maneuvering logics, but it can also be used to evaluate the tactical implications of perturbations to aircraft performance or supporting systems. The TMS can simulate air combat between any number of engagement participants, with practical limits imposed by computer memory and processing power. Aircraft are modeled using equations of motion, control laws, aerodynamics, and propulsive characteristics equivalent to those used in high-fidelity piloted simulations. Data bases representative of a modern high-performance aircraft with and without thrust-vectoring capability are included. To simplify the task of developing and implementing maneuvering logics in the TMS, an outer-loop control system, the tactical autopilot (TA), is implemented in the aircraft simulation model. The TA converts guidance commands by computerized maneuvering logics from desired angle of attack and wind-axis bank-angle inputs to the inner loop control augmentation system of the aircraft. The capabilities and operation of the TMS and the TA are described
Conceptualizing gendered vulnerability to climate change in the Hindu Kush Himalaya:
Not all women or all men are equally vulnerable. Manifestations of vulnerability to climate change vary in different groups of people, based on their position in a social and gender structure in a particular location and at a particular time. We need to understand the pre-existing conditions, what we term âcontextual conditionsâ that underlie experiences of vulnerability and lead to its complexity and reproduction. This paper is based on a literature review and takes the standpoint that not only is gender a powerful and pervasive contextual condition, but that it intersects with other contextual conditions to shape vulnerabilities. Further, gender and other contextual conditions also influence and are influenced by socioeconomic drivers of change to produce differential gendered vulnerabilities. Therefore, manifestations of gendered vulnerability to climate change are the result of complex and interlinked factors, which cannot be simplified for the sake of efficiency. This paper offers a conceptual framework bringing together these interlinkages and intersectionalities in understanding differential gendered vulnerabilities
California Property Tax Exemptions, Exclusions, Immunities, and Restrictions on Fair Market Valuation--Or, Whatever Became of Full Value Assessment?
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